Background/Objective: This study investigated the associations between dietary patterns and subjective cognitive function among older Japanese adults and examined whether these associations differed according to sleep duration. Methods: This longitudinal cohort study was conducted using data from the Community Empowerment and Care study (2017–2020). Data were obtained from the Community Empowerment and Care Study of the T-Village, Aichi Prefecture, Japan. Latent class analysis was used to identify dietary patterns based on the intake frequencies of seven food groups. Logistic regression models assessed the associations between dietary patterns and subjective cognitive function stratified by sleep duration (optimal: 7–8 h; unfavorable: 8 h). Results: Three dietary patterns were identified (diverse, balanced, restricted). Compared with the restricted pattern, the diverse (odds ratio = 0.13, 95% confidence interval: 0.07–0.26; p < 0.0001) and balanced patterns (odds ratio = 0.33, 95% confidence interval: 0.18–0.62; p = 0.0006) were associated with lower odds of poor subjective cognitive function. Associations were broadly similar across sleep groups, and interaction testing was not significant. Conclusions: Dietary quality was associated with better subjective cognitive function, particularly among older adults with unfavorable sleep duration. The study findings underscore the need for integrated lifestyle interventions that target both nutrition and sleep in aging populations.

Background/Objective: This study investigated the associations between dietary patterns and cognitive function among older Japanese adults and examined whether these associations differed according to sleep duration. Methods: This longitudinal cohort study was conducted using data from the Community Empowerment and Care study (2017–2020). Data were obtained from the Community Empowerment and Care Study of the T-Village, Aichi Prefecture, Japan. Latent class analysis was used to identify dietary patterns based on the intake frequencies of seven food groups. Logistic regression models assessed the associations between dietary patterns and cognitive function stratified by sleep duration (optimal: 7–8 h; unfavorable: 8 h). Results: The following three dietary patterns were identified: diverse, balanced, and restricted. Diverse (odds ratio [OR], 0.44) and balanced (OR, 0.39) diets were associated with lower odds of cognitive decline. Stratified analysis revealed stronger protective effects of these diets in those with unfavorable sleep. Conclusion: Dietary quality plays a key role in cognitive health and may be particularly beneficial for older adults with suboptimal sleep durations. The study findings underscore the need for integrated lifestyle interventions that target both nutrition and sleep in aging populations.

This study examined the relationship between changes in social interactions and sleep status, specifically sleep duration and restoration, among older adults in Japan to inform interventions for healthy aging. A 6-year longitudinal study (2017–2023) was conducted under the Community Empowerment and Care Project in suburban Japan. A total of 473 older adults with normal sleep in 2017 were followed. Sleep duration (< 6 h defined as deprivation) and sleep restoration (subjective restfulness) were assessed according to national guidelines. Social interaction was measured using the 18-item Index of Social Interaction (ISI). Changes in the ISI were analyzed continuously and categorically. Lo-gistic regression models were used to examine the association between ISI changes and sleep outcomes. After six years, 16.3% of the participants experienced sleep deprivation, and 26.2% reported non-restorative sleep. Declining ISI scores were significantly asso-ciated with a higher risk of sleep deprivation and non-restorative sleep. Persistently low or declining ISI scores increased the odds of poor sleep. A one-point ISI increase re-duced the risk of sleep deprivation and non-restorative sleep, even after adjusting for confounders. Negative or persistently low social interaction is linked to worse sleep outcomes; maintaining or improving social interaction may protect sleep quality.